Related Art
Conventionally, the running vehicle, when intended to reduce a steering force, is equipped with a power steering system. The power steering system supplies oil to a power cylinder correspondingly to a rotation of handle so as to extend or contract a movable side of the power cylinder to allow the steering wheels to laterally turn. It is well-known that in a case where the front wheels can be driven to be used as the steering wheels, the power cylinder is provided over the front axle casing and a tie rod is laterally turned through an arm, or the power cylinder is laterally disposed and extends in parallel to the axle casing so as to connect one of the movable side or the fixed side of the power cylinder to the axle casing and the other to the knuckle arm for extending or contracting the power cylinder, thereby enabling the vehicle to be steered. The power cylinder, when laterally disposed, can also be disposed in front or rear of the front axle casing, and, when protected from an obstacle in front, is disposed at the rear of the same, which structure is disclosed in, for example, the Japanese Utility Model Publication No. Hei 1-37337.
As the above-mentioned, where the power cylinder is disposed laterally of the front axle casing and at the rear side thereof, the power cylinder does not traverse the lateral center of the vehicle body, but is disposed not to interfere with a transmission shaft or an input shaft for transmitting power to the front axle casing so as not to be vertically high. However, when a pivotally supporting portion at the fixed side of the power steering cylinder is disposed outwardly (at the side of the knuckle arm) from the laterally center of the front axle casing, the stroke of the power cylinder cannot be made larger, whereby the power cylinder must be reduced in length in itself and the pivotally supporting portion or the power cylinder is reduced in distance from the center of rotation of the knuckle arm so that the tie rod is set in the position where the rod is movable in a specified range in the short stroke. Hence, the power cylinder should be made larger in capacity so as to enlarge the steering force of the front wheels. Hence, the pivotally supporting portions of the power cylinder with the knuckle arms and axle casing are increased in strength and also the axle casing is strengthened in itself. Accordingly, the power cylinder should be of high performance and the axle casing and pivotally supporting portions are larger in thickness to cause weight increment, resulting in a high manufacturing cost.